The present invention relates to an optical system for determining the curvature or modification made to the curvature of an object.
The invention is applicable, more particularly but not exclusively, to determining the variation of curvature of the cornea of the eye, in its central zone, during a surgical treatment thereof, particularly by photoablation, with the aid for example of the apparatus described in document EP-A No. 0 191 688, and especially adapted for the treatment of zones not exceeding some millimeters diameter.
Such a surgical apparatus is intended to modify the curvature of the cornea by photodecomposition of the corneal matter. In fact, it is known that certain disorders, such as myopia, hypermetropia and astigmatism, may be treated by modification of the curvature of the cornea.
During such surgical treatment, it is essential to be able to determine, precisely, reliably and rapidly, the variation during treatment of the curvature of the central zone of the cornea in order, at each elementary step of the treatment, on the one hand, to measure the effective ablation of corneal matter during said step and, on the other hand, to modulate, as a function of said ablation, the amplitude of the following step, it being understood that it is crucial not to exceed, at the end of treatment, a predetermined modification of curvature.